The present invention relates to a sputter cathode with a flat, plate-shaped target formed from at least one part and with a trough-shaped yoke arranged behind the target with a middle web or bridge and with magnets for generating closed tunnels of electric field or flux lines curved in an arc in front of the target surface. Approximately strip-shaped or annular blanks of magnetically conducting sheet metal are placed in the plane between the target and the front surface of the trough edge of the yoke, which front surface faces the target, and with blanks covering the area above the front surface of the trough edge and of the middle web and with further blanks covering a part of the area between the front surface of the middle web and the front surface of the trough edge and with all sheet-metal sections together forming gaps extending approximately parallel to the front surfaces.
A sputter cathode of the type in question is known (U.S. Pat. No. 4,865,708) in which segments of permeable material are arranged between the target on the one hand and the magnetic yoke on the other hand in the plane of the magnet rows, namely, below the plane of the front magnet surfaces facing the target in order to concavely deflect the tunnel of curved field lines forming in front of the target in order to make possible in this manner a wider erosion trough on the target and therewith a higher target service life.
Furthermore, a sputter cathode has been suggested (DE 196 22 606.6) with a base cathode body with a plate-shaped target as well as with a magnet yoke arranged behind the target and with two closed series of magnets with different polarities arranged in an oval or rectangular configuration and coaxially to each other in a plane parallel to the target plane. Sheet-metal blanks or appropriately configured partial blanks of magnetically conductive material are placed in the plane between the target and the front surfaces of the magnets facing the target. Two of the sheet-metal blanks or partial blanks have a frame-shaped configuration. The two arced sections of the sheet-metal blanks uniting straight longitudinal parts to each other have an edge course deviating from a circular arc, e.g. an elliptical, parabolic or even irregularly arced edge course so that the gap formed by two adjacent, arced sections has an irregular course of width.
In addition, a sputter cathode has been suggested (DE 196 22 607.4) with a magnet yoke arranged behind the target with two rows of magnets arranged in oval or in rectangular configuration and coaxially to each other in a plane parallel to the target plane with the magnets three sheet-metal blanks or groups of partial blanks placed into the plane between the target and the front surfaces of the magnets facing the target. Two of these sheet-metal blanks or partial blank groups cover the area above the magnets and the third sheet-metal section or the third group covers a part of the area between the magnet rows and all sheet-metal blanks together form two gaps extending approximately parallel to the magnet rows.
An object of the present invention is to arrange the magnets and the segments in such a manner that on the one hand a flat and especially wide erosion trough forms during the sputtering operation, the most optimum target removal of metal occurs and that on the other hand the area between the two parallel magnet tunnels forms as narrowly as possible.
In addition, the segments should be formed in such a manner that they can be manufactured as economically as possible and that their rigidity is dimensioned in such a manner that they can be installed into the cathode without further supporting or holding means.